Description
DEMO MANUAL DC1765A
LTC6957-1/LTC6957-2
Low Phase Noise, Dual LVPECL or LVDS
Output Buffer/Driver/Logic Converter
Demonstration Circuit 1765A features the LT C®6957-1/
LTC6957-2, a low phase noise, dual LVPECL or LVDS
output buffer/driver/logic converter.
The DC1765A provides 0.5" spaced SMA connectors for
the differential inputs and outputs. The inputs are terminated to on-board 50Ω resistors. The LVPECL outputs
of the DC1765A-A are individually biased through 130Ω
resistors to ground and then AC-coupled. The transmission lines are 50Ω, making the outputs suitable to drive
50Ω input impedance instruments. The LVDS outputs
of the DC1765A-B are terminated with 100Ω differential
and are DC-coupled. The DC1765A allows the user to
take advantage of the shutdown and bandwidth selection
features of the LTC6957. The DC1765A can operate with
a single-ended or differential sine wave or square-wave
input signal. Supply the DC1765A with 3.3V and it is
ready to function. The DC1765A offers extra component
population options to make it compatible with different
logic signal types.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Figure 1. DC1765A Inputs and Outputs
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DEMO MANUAL DC1765A
Quick start proceDure
The DC1765A is very straightforward to operate. Refer to
Figure 1 for the following discussion.
DC1765A Configuration
1. Apply a low-noise and low-spurious 3.3V supply between
the V+ (E1) and GND (E2) turrets.
2. Connect a low phase-noise (or jitter) single-ended or
differential input signal to IN+ (J1) and/or IN– (J2)
SMA connectors. Refer to the LTC6957 data sheet for
appropriate input signal types and levels.
3. Connect either of the outputs (OUT1, J3 and J4 or OUT2,
J5 and J6) to a high-speed scope, spectrum analyzer or
a signal analyzer to start the evaluation of the LTC6957.
4. Configure the input bandwidth of the LTC6957 with the
use of FILTA (JP1) and FILTB (JP2) jumpers. Follow the
instructions given in the LTC6957 data sheet to choose
the correct bandwidth given an input signal.
5. Shut down an unused output by using jumper SD1 (JP3)
to shutdown OUT1 or jumper SD2 (JP4) to shutdown
OUT2.
DC1765A Reconfiguration
The DC1765A is flexible and allows the connectivity of a
variety of input and output signal types. The DC1765A is
configured as shown in the schematic diagram. However,
the DC1765A allows the installation of different input and
output configurations to adapt to a variety of logic signals. Refer to the Applications Information section of the
LTC6957 data sheet for all possible connectivity options
that can be implemented by modifying the DC1765A.
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dc1765af
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